Sound-reproducing mechanism



Sept. 22, 1925. 1,554,561

' DE FOREST SOUND REPRODUGING MECHANISM Filed Aug. 2, 1919"II/IIIIIIIIIIA v INVENTOR MAW ATTORNEY IIII'IIIIIHII l lg| PatentedSept. 22, 19 25.

UNITED STATES 1,554,561 PATENT OFFICE.

LEE an Banner, on NEW YORK, 11. Y., AssroN-on, BY nsnn ASSIGNMENTS, r DEronns'r PHONOFILM conromrrolv, or JERSEY CITY, NEW JERSEY, A ooaPonATIO'R' OF DELAWARE.

SOUND-BEPRODUCIN G MECHANISM.

Application filed August 2, 1919.- Serial No. 314,856.

To all whom it may concern:

Be it known that I, LEE on Fonns'r, a citizen of the United States,residing at New York, county and State of New York, have a made acertain new and useful Invention in Sound-Reproducing Mechanism, ofwhich the following is a specification.

This invention relates to sound reproducing mechanism for reproducingsound from N sound records, such, for example, as phonograph records, orthe like.

The object of the invention is to provide means for reproducing fromsound records the sound recorded thereon in a simple and efficientmanner.

A. further object of the invention is to rovide means in a device of thecharacter described whereby all .-parasit-ic noises and disturbancesincident to the present methods 0 employed for thG'IGPI'OdUQtlOIl ofrecorded sounds are eliminated.

A. further object of the invention is to employ in connection with thereproducing of recorded sounds a thermionic electrical device. I

A further object of the invention is to provide a thermionic deviceofnovel construction and efficient operation for this and similar urposes.

Further objects-of the invention will appear more fully hereinafter.

The invention consists substantially in the construction, combination,location and a relative arrangement of arts, and the elec- 85tricalcircuits associated therewith, all as will be more fullyhereinafter set forth, as shown by the accompanying drawing, and finallypointed out in the appended claims.

Referring to the drawing:

Fig; 1 is a diagrammatic view of a sound reproducing system embodying myinvention.

Fig. 2 is a similar view of a slightly modified construction.

Fig. 3 is a dia rammatic 'view of the thermionic device sl iown in sideelevation.

' Fig. 4- is a front view of the same.

Fig. 5 is a similar view of a slightly modified construction taken inside elevatlon.

50 Fig. 6 is a front view of the same.

Fi 7 is a detached detail view in pers ective of oneelectrode memberemployed t erein.

The same part is designated by the same reference character whereverthroughout th several views.

In the reproduction of recorded sound,

such for example, as is recorded on phonoit occurs graph records, or thelike, I have discovered that by using a thermionic device, either ofspecial ponstructi'on, or of the audion type, parasitic no1ses lncidcntto the repro ment of the reproducing device. It will be apparent thatwith this system inasmuch as the sound is produced in its ultimatereproduction by the movement of the reproducing device alone theparasitic noises now common in the reproduction ofrecorded sound, anddue largely tothe frictional contact of the reproducing device with thesound record, is completely eliminated. My

this manner, and therefore while I have shown and will now describe byreference to the diagrammatic illustration of the principle of myinvention, several dilierent means for-accomplishing this purpose, IWish it to'be understood that my invention in its broad scope as definedin the claims is not to be limited to the particular forms selected forthe purpose of illustration.

Referring to Fig. 1, I show diagrammatically at 1a sound record, theform selected the principle of operation of all sound recorders of thisnature is to impart movement to the needle in accordance with the soundrecord, whether that movement be vertically over the hill and dale typeof record, as it is called, or horizontally. In accordance with 80invention may be carried out practically in my invention I mount on theend of the tone arm 2 the thermionic device 3, which may vary inconstruction in many respects. I haveshown in Figs. 3 and 4 oneconstruction selected for illustration, which consists of an evacuatedvessel of any suitable material,

.- preferably of glass, in which is located a plate electrode 4 and afilament electrode 5, which electrodes are separated from each otherwithin the vessel. The filament electrode is provided with two leads 6and 7, which are connected'to the opposite terminals of a suitablesource of current 8, controlled in any desired manner as to strength,duration, etc., whereby the filament is heated to the required degree ofincandescence for the most eflicient operation of the device. The plateelectrode 4 is mounted in the vessel 3 by means of a flexible member 9to allow a vibratory movement of the plate member 4, which is madecomparatively large and heavy relative to the filament electrode 5. Theplate electrode is connected by a wire 10 through an electricallycontrolled sound reproducer illustrated at 11 to a source of currentillustrated at 12, and from thence to the line 6 of the filamentelectrode. The sound reproducer 11 may be of any suitable type or form,for example, it may be a loud speaking horn or the ordinary telephonereceiver. From the foregoing it will be seen that a continuous flow ofcurrent is secured within the vessel from the filament to the plateelectrode, the principle of operation being long established in theradio or wireless art with no sound being produced by the horn or receiver 11. As soon, however, as the disk 1 is revolved in the usual wellknown manner causing vertical movement of the tone arm 2 relative to thehorizontal plane of the disk where the hill and dale type of record isemployed, the thermionic device 3 being positioned with the plane of theplate electrode parallel to the plane of the disk 1 in its mounting onthe tone arm 2 the space between the electrodes 4 and 5 is varied inaccordance with the up and down movement of proportional to the verticalvibratory movement of the tone arm 2 with the result that the continuousflow of current through the thermionic device from the filament to theplate electrode thereof is interrupted or varied, causing currentvariations in the circuit extending between the and the filament, whichvariations are reproduced in the horn 11 in the form of sound wavescorresponding to the sound waves employed' to form the record which inturn causes the variations in the circuit. If desired, a suitableamplifying device may be inserted in the plate filament circuit toamplify 'the current variations secured 'by the plate electrode movementof the member 2, and in In this infilament electrode 14 of the audion 15of the usual .construction. The filament electrode 14-. is heated bymeans of battery 16 and controlled through the resistance 17 in theusual well known manner. The plate electrode 18 of the audion 15 isconnected with the battery 19 through the horn 11 to the filament 14 1nthe usual well known manner. By this arrangement the current variationsset up in the line 10 and 11 are fed into the filament or input circuitof audion amplifier 15 causing corresponding but greatly magnifiedvariations in the plate filament or output circuit of the audionamplifier 15, in which output circuit is located the loud speaking hornor other electrical sound reproducingdevice.

I have also discovered that the same principle may be employed to thethree electric audion construction as illustrated in Figs. 5, 6 and 7,in which instance I prefer to employ the grid electrode as the vibratoryelectrode rather than the plate electrode as illustrated in the twoelectrode thermionic devices. In Figs. 5 and 6 I show the vessel 3evacuated in the usual manner with the filament electrode 20 providedwith the two terminals 21 and 22 sealed through the vessel in the usualmanner, and the plate elec trode 22 rigidly supported as at 23 with theterminal thereof 24 sealed through the vessel in the usual manner. Thegrid electrode 25 inthis instance is made comparatively large and heavyand is supported by the vessel as at 26 by flexible spring members. Thegrid electrode 25 is located between the plate and filament electrodesas is usual in the audion art. The device is located on the end of thetone arm in the manner hereinbefore described, the only difference beingthat instead of-a single circuit connecting the plate and filament as inthe form shown in Fig'. 1, the grid and filament will be connectedtogether and the plate and filament will be connected together throughthe battery and loud speaking horn in the manner hereinbefore described.From the foregoing it will be apparent that where the lateral wave typeof sound record is employed it is merely necessary to turn device 3 inits mounting on the tone arm in such a manner as to cause the movableelectrode,

that is,.elec tr'ode 4 in the form shown in grid ' claims, therefore,what I claim as new and useful and of my own invention and desire theart Without departing from the spirit and scope of my invention asdefined in the to secure by Letters Patent is,

1. The combination with a sound record,

of a member mounted to be moved by and n accordance with said record, anevacuated vessel associated with said member and containing therein aplurality of electrodes,

one of said electrodes being mounted for movement, means for heating oneelectrode, means for moving said movable electrode by and in accordancewith the movements of said member, and means controlled by the movementsof said movable electrode for reproducing the recorded sounds.

2. The combination with a sound record, of a member mounted to be movedby and in accordance with said record, an evacuated vessel carried byand moved with said member, said vesselcontaining therein a plurality ofelectrodes, one of said electrodes bein mounted for movement, means 'forheating one electrode, means for moving said movable electrode by. andin accordance with the movements of said member,electric circuits forsaid electrodes, a translating device and a source of current. includedin one of said circuits.

- 3. The combination of a sound record and a thermionic device movablymounted and having electrodes therein, meansefor heating one of "saidelectrodes, means for causing variations of space between saidelectrodes by and inaccordance with the movements of said device, andmeans or' translating said movements into audib vibrations.

4. The combination of athermionic vessel movably mounted and a soundrecord for causing said vessel to move, separated electrodes containedin said vessel, one of said electrodes being of' relatively great Weightand mounted to respond tov the movements of said vessel, and circuitsfor said electrodes.

5. A movable vessel containing therein a hot and a plurality of coldelectrodes, means for imparting movement to' said vessel to therebycause one of said cold electrodes to respond by and in accordance withthe movemnts of said vessel, and an electric circuit controlled by themovements of said movable electrode.

6. A vessel mounted to move by 'and in accordance, with recorded soundand containing therein a hot electrode and an anode spaced therefrom, amovable conducting body interposed between said hot electrode and saidanode, means for impartin movement to said conducting body b. an inaccordanbe with the movements 0 said vessel, an electric circuitcontrolled by the movements of said conducting body for causing fluxvariations therein, and means for translating said variations intoaudible vibrations.

7. A movable vessel containing thereini filament, grid and plateelectrodes, means for imparting movement to said grid electrode by andin accordance with predetermined, positive movements of said vessel forvarying the effective distance between said electrodes and means fortranslating said electrode movements into audible vibrations. i

I 8. A movable vessel containing therein filament, grid and plateelectrodes, means for imparting predetermined movements to the strengthof a constantly flowing current, i

and translating the current variationinto Q sound waves, I

10.. The method of electrically reprodu recorded sounds, which comprisesoscillating a thermionic vessel in synchronism with grooved inequalitieson a sound record to thereby positively vary the space relations betweenelectrodes in said vessel, and to utilize said electrode variations toinduce varying current flux in an associated circuit for translatingsaid current flux variations into audible vibrations.

In testimony whereof I have hereunto set my hand on this 24th day ofJuly, A. D, 1919.

LEE DE FORE-ST.

